'\" te
.\"  Copyright 1989 AT&T
.\"  Copyright (c) 2006, Sun Microsystems, Inc.  All Rights Reserved
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
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.TH DATAMSG 9F "Feb 17, 2023"
.SH NAME
datamsg \- test whether a message is a data message
.SH SYNOPSIS
.nf
#include <sys/stream.h>
#include <sys/ddi.h>



\fBint\fR \fBdatamsg\fR(\fBunsigned char\fR \fItype\fR);
.fi

.SH INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
.SH PARAMETERS
.ne 2
.na
\fB\fItype\fR\fR
.ad
.RS 8n
The type of message to be tested. The \fBdb_type\fR field of the
\fBdatab\fR(9S) structure contains the message type. This field may be accessed
through the message block using \fBmp->b_datap->db_type\fR.
.RE

.SH DESCRIPTION
The \fBdatamsg()\fR function tests the type of message to determine if it is a
data message type (\fBM_DATA\fR, \fBM_DELAY\fR, \fBM_PROTO\fR, or
\fBM_PCPROTO\fR).
.SH RETURN VALUES
\fBdatamsg\fR returns
.sp
.ne 2
.na
\fB\fB1\fR\fR
.ad
.RS 5n
if the message is a data message
.RE

.sp
.ne 2
.na
\fB\fB0\fR\fR
.ad
.RS 5n
otherwise.
.RE

.SH CONTEXT
The \fBdatamsg()\fR function can be called from user, interrupt, or kernel
context.
.SH EXAMPLES
The \fBput\fR(9E) routine enqueues all data messages for handling by the
\fBsrv\fR(9E) (service) routine. All non-data messages are handled in the
\fBput\fR(9E) routine.
.sp
.in +2
.nf
1 \fIxxx\fRput(q, mp)
2      queue_t *q;
3      mblk_t *mp;
4 {
5    if (datamsg(mp->b_datap->db_type)) {
6            putq(q, mp);
7            return;
8    }
9    switch (mp->b_datap->db_type) {
10    case M_FLUSH:
		       \&.\|.\|.
11    }
12 }
.fi
.in -2

.SH SEE ALSO
.BR put (9E),
.BR srv (9E),
.BR allocb (9F),
.BR datab (9S),
.BR msgb (9S)
.sp
.LP
\fIWriting Device Drivers\fR
.sp
.LP
\fISTREAMS Programming Guide\fR
